The TIU said the three had admitted to betting on tennis matches at ITF Futures tournaments at which they were officiating last year.
"They also manipulated scores inputted into the official scoring system, for betting-related purposes and personal profit," it said in a statement.
The three were named as Anucha Tongplew, Apisit Promchai and Chitchai Srililai.
The ITU said the lifetime bans were effective immediately and prohibit each "from ever officiating at, or attending, any sanctioned events organised or recognised by the governing bodies of the sport."
The ITF Futures tournaments, held in more than 70 countries, are the lowest rung on the professional ladder for players seeking ranking points.
(Reporting by Alan Baldwin; Editing by Raissa Kasolowsky)
